Discomfort glare caused by white LED light sources - Effect of light sources position

Lighting that uses light emitting diodes (LEDs) is likely to be widely used in the future. However, the effect of the glare from an LED light source on user comfort has not been clarified. To clarify the characteristics of the glare from a white LED light source and its effect on comfort, we conducted the following experiment. A white LED module was used for the light source, and the distance between the subject and light source, and its angle were varied. The subject then gave a value to how comfortable or uncomfortable they felt. When the LED was in the subject's sight and 10 degrees above it, the level of discomfort was assigned the highest and the second highest value respectively. However when the LED was viewed horizontally, the observation distance was large, and the angle was 10 degrees, the glare was assigned a near value. Moreover, when the line of sight was horizontal and the LED was at an angle between 45 and 65 degrees, it tended to produce feeling of discomfort. Furthermore, at an almost near value, compared with the results gained from experiments that used an imitation light source and that investigated the level of discomfort caused by the glare from a white LED light source, the use of an imitation light source appears to be valid.